The invention relates to a data carrier for the contactless communication with a communication station designed for this, and to a communication station for the contactless communication with a data carrier designed for this, as well as to an integrated circuit for a data carrier for the contactless communication with a communication station designed for this.
Such a data carrier and such an integrated circuit as well as such a communication station are described in, for example, the patent document WO 99/57681 A1 and are consequently known. The known data carrier has an integrated circuit by means of which, in addition to other circuit sections, a direct voltage generation circuit is realized, which circuit includes a rectifier stage further includes voltage limiting means, with the aid of which the d.c. supply voltage which can be generated with the aid of the direct voltage generation circuit can be limited to a maximum value, when necessary. Such a limitation is necessary, for example, when a data carrier is situated close to a communication station and is thus situated in an area with a high field strength of a communication fields that can be generated by the communication station, because in the absence of the voltage limiting means the high field strength would result in an excessive d.c. supply voltage on the output of the direct voltage generation circuit. The operation of the direct voltage generation circuit and, particularly, the operation of the voltage limiting means leads to generation of heat in the known data carrier, which results in a temperature rise in the known data carrier. Such a temperature rise has only comparatively insignificant consequences when the integrated circuit, by means of which both the direct voltage generation circuit and the voltage limiting means are realized, has a comparatively large surface area and can therefore handle comparatively large temperature rises. However, such temperature rises pose a problem when an integrated circuit for a data carrier adapted to provide contactless communication with a communication station is miniaturized to a higher degree than in the case of the aforementioned prior-art solution, i.e. is to be realized on a smaller chip area, because as a result of such temperature rises there is a risk that at least a part of the integrated circuit is damaged or even destroyed owing to excessively high temperatures.
It is an object of the invention to preclude the risk of adverse effects on a data carrier and on an integrated circuit in the case of further miniaturization of the data carrier and of the integrated circuit even in operational situations in which comparatively large temperature variations occur during operation, which without the provision of the measures in accordance with the invention would lead to operating temperatures outside a given permissible range of operating temperatures in the data carrier and in the integrated circuit.
In order to achieve the aforementioned object, characteristic features in accordance with the invention are provided in a data carrier in accordance with the invention, in such a manner that a data carrier in accordance with the invention can be characterized in the manner defined hereinafter, namely:
A data carrier adapted to provide contactless communication with a communication station and including an integrated circuit and including a direct voltage generation circuit, which serves to generate and to supply a d.c. supply voltage for the data carrier, and including detection means for detecting the temperature prevailing in the environment of the detection means in the data carrier, with the aid of which detection means a representation signal representative of the prevailing temperature can be generated, and including initiation means adapted to receive and to process the representation signal and adapted to initiate a change of the temperature in the data carrier.
In order to achieve the aforementioned object, characteristic features in accordance with the invention are provided in an integrated circuit in accordance with the invention, in such a manner that an integrated circuit in accordance with the invention can be characterized in the manner defined hereinafter, namely:
An integrated circuit for a data carrier for providing contactless communication with a communication station, including a direct voltage generation circuit, which serves to generate and to supply a d.c. supply voltage for the integrated circuit, and including detection means for detecting the temperature prevailing in the environment of the detection means in the integrated circuit, with the aid of which detection means a representation signal representative of the prevailing temperature can be generated, and including initiation means adapted to receive and to process the representation signal and adapted to initiate a change of the temperature in the integrated circuit.
As a result of the provision of the characteristic features in accordance with the invention it is achieved in a comparatively simple manner and with only low additional cost that the temperature in a data carrier and in an integrated circuit for such a data carrier can be changed, i.e. increased or reduced depending on the situation, so as to keep the operating temperature in the data carrier and the integrated circuit within a desired specified range of operating temperatures.
In a data carrier in accordance with the invention and in an integrated circuit in accordance with the invention the initiation means may be adapted to initiate a temperature increase, which may be required for example when a data carrier in accordance with the invention and an integrated circuit in accordance with the invention should operate correctly in deep-freeze environment. However, it has proved to be particularly advantageous when the initiation means are adapted to initiate a reduction of the temperature in the data carrier and in the integrated circuit. This is of particular advantage because in a number of uses of a data carrier and an integrated circuit for such a data carrier a comparatively strong heating may occur, particularly when the integrated circuit should be realized on a minimal chip area, an undesired temperature rise then being precluded with the aid of the measures in accordance with the invention.
In a data carrier in accordance with the invention and in an integrated circuit in accordance with the invention the temperature can be influenced with the aid of an input resistance of an input circuit because the energy received and further processed by a data carrier in the range of operation in which a temperature change, for example a temperature rise, is possible, is proportional to the input resistance of an input circuit and can consequently the energy input can be changed by changing the input resistance, which results in a change of the temperature in the data carrier and in the integrated circuit.
In a data carrier in accordance with the invention and in an integrated circuit in accordance with the invention it is also possible to use a transmission resonant circuit, provided in such a data carrier for receiving a communication signal transmitted to the data carrier by a communication station, for changing the temperature, which is possible because the energy input by means of such a transmission resonant circuit depends on the resonant frequency of the transmission resonant circuit, as a result of which the energy input into a data carrier can be changed in a comparatively simple manner by changing the resonant frequency of the transmission resonant circuit, which leads to a change of the temperature prevailing in the data carrier and in its integrated circuit. For changing the resonant frequency of the transmission resonant circuit use can be made of capacitors which can be switched into and out of the transmission resonant circuit. Changing the resonant frequency may alternatively be effected by switching inductances into or out of the circuit.
However, with a data carrier in accordance with the invention and an integrated circuit in accordance with the invention it has also proved to be very advantageous when the initiation means are adapted to support the transmission of a transmission signal, which corresponds to the representation signal representative of the temperature prevailing in the data carrier and in the integrated circuit, from the data carrier to a communication station. This embodiment has the advantage that the change of the temperature prevailing in the data carrier and in the integrated circuit is initiated in the data carrier and in the integrated circuit but that the means for changing the temperature in the data carrier and in the integrated circuit are not included in the data carrier or the integrated circuit but in the communication station which is adapted to provide contactless communication with the data carrier and the integrated circuit.
In the above context it has proved to be very advantageous when a communication station in accordance with the invention includes station processing means for processing the transmission signal transmitted by the data carrier and received by the communication station and further includes control means which can be influenced by the station processing means and with the aid of which the energy content of a communication signal transmitted from the communication station to the data carrier can be changed. This has the advantage that the measures for changing the temperature in a data carrier in accordance with the invention and in an integrated circuit in accordance with the invention are implemented in the communication station in accordance with the invention, which has the advantage that, if required, substantially more expensive and more intricate means and measures for changing the temperature in a data carrier and in an integrated circuit can be realized in a comparatively cheap manner.
The above-mentioned as well as further aspects of the invention will become apparent from the embodiments described hereinafter by way of example and will be elucidated with reference to these examples.
The invention will now be described in more detail with reference to the drawings, which show four embodiments which are given by way of example but to which the invention is not limited.